Hydraulic apparatus



Oct. 25, 1938. G. hLRUssELL;

HYDRAULIC APPARATUS Filed March 5, 1930 5 sheets-sheet 1 ,Bai A- N1 Oct.25, 193.8. G. J. RUSSELL HYDRAULG APPARATUS Filed March 5, 1950 5Sheets-Sheet 2 Oct. 25, 19318. G. J. RUSSELL- HYDRAULIC APPARATUS FiledMarch 5, 1950 5 Sheets-Sheet 5 oct. 25, 193s.

5 Sheets-Sheet 4 Filed March 5, 193') ugs-.sell

Oct. 25, 19318. G. J. RUSSELL`v 2,134,673

` HYDRAULIC APPARATUS l Filed March s, 1930 5 sheets-sheet 5 44 Patentedoca-'25, 193s 2,134,673

UNITED STATES PATENT OFFICE HYDRAULIC APPARATUS George J. Russell,Waltham, Mass., assigner ofl l l(Tile-half to lEverett S. Emery,Lexington,

Application March 5, 1930, Serial No. 433,491

3 Claims. (Cl. 60-52) ciprocatery motion to a member and to means foracter. effecting such movements atldifferent rates of In the drawings:speed on the working and return strokes of Fig. 1 is a top plan view ofa breaching ma- 5 various machines such for example as on the chine;cutting and return strokes of breaching ma- Fig. 2 is also a plan viewof a portion of the chines. apparatus shown in Fig. 1, but showing theparts In many types ef machines itis advantageous"` in differentrelative positions; to use one or more power cylinders for advanc- Fig.3 is a longitudinal vertical section of the 10 ing and returning a toolor other instrumentality. machine with the pilot withdrawn and the otherv A reversible or other type of pump may be proparts arranged as lshownin Fig. 2; vided for supplying pressure uid to the cylinders Fig. 4 is asection taken substantially along the and in such cases it is moreeconomical to use-a line 4-4 of Fig. 1 with the parts arranged as pumphaving approximately the capacity reshown in Fig. 2; 15 quired to makethe working stroke at the desired Figs. 5, 6, and 7 are transversevertical sections speed. However when this is done the pump,- due takenon substantially the same horizontal plane toits limited capacity, canonly effect the return through the body of the control unit to show thestroke at approximately the same speed as the parts in differentrelative positions, Figs. 5 and 6 working stroke. This procedure resultsin a conshowing diierent 'sections of the choke valve, 20 siderable lossof time and -the desirability of While the latter is shown in elevationin Fig. 7; speeding up the return stroke will be apparent. v Fig. 8 is asection taken substantially along To remedy this condition Withoutincreasing the line 8-8 of Fig. 5;

the capacity of the pump over that vrequired for Fig. 9 is a sectiontaken along the line 9--9 of the working stroke, itis proposed to equipthe, Fig. 7 ;,and 25 cylinders with pistons having unequal pressure Fig.10 is an elevational view of apparatus for areas on their oppositefaces, the greater area reversinga pump.

being effective on the return stroke, and to pro- The features of thisinvention, Fig. 1, are i1- vide for by-passing uid around the piston enlustrated as embodied in a breaching machine of the return stroke. Thedelivery side of the pump the general type disclosed in my prior PatentNo. 30 is connected toboth ends of the cylinder during 1,431,437, issuedJanuary 22, 1924. and also in mv this return stroke and movement of thepiston l copending applicationSerial No. 433,490, filed on is produceddue to the difference in effective areas even date herewith (iSSlledNovember 21. 1933, on the opposite faces thereof. The piston then asPat. No. 1,936,073). This machine COIIIDISeS acts as a pump to forceiluid from one end of the a bed I0 which is supported on end pedestalsIl 35 cylinder through the by-pass to the other end and I2 and isprovided with transverse end memof the cylinder. The volume delivered'to the bers I3 and I4 and with longitudinal side members cylinder, bythe combined ilow through the byl5 .and |'7- Intermediate the endmembers the pass and from the pump', is so greatly increased bed isprovided with transverse members I8', I9 that the return stroke is very'rapid. In cases and 2|, the latter being fitted with an external 40where this system has been empmye'd it has been guide 22 which slidablyreceives and supports necessary to slow down the return stroke to apieces 0f previously breached SOCk 23 in Which speed far below themaximum attainable speed the rear end of the breaching 19001 24 iSSupportedin order to avoid damage to the apparatus or to During thebroaching stroke a pilot 26, in the auxiliaries due to the highpressures and/or member I9, is advanced to the rightas shown in`velocities resulting from the combined new and Fia-3. dotted lines. tcengage the rear end cf the greatly increased volume. breach 24 to holdthe latter stationary. 'Ihe Objects of the present invention are toimprove DilOt iS COImeCted 130 the IOd 271 0f a plunger 28 a system ofthis kind so that the return stroke can Which is slidable in acylindrical guide 29, this be made at greater speeds without damaging orguide being supported on the transverse member otherwise interferingwiththe operation of the I8. The transverse member I9 carries anexterapparatus or with auxiliaries associated with the nal cuide 3|which slidably receives the pilot 26 apparatus; to provide improvedapparatus of this and red 2T fOr guiding and SUPPOlting the lettercharacter for operating broaching machines; to during advance andwithdrawal of lche pilet- A provide improved broaching apparatus; toproguide plate 30 is mounted on the guide 3|.slidably 55 vide improvedmeans for controlling apparatus of to receive the pilot. The externalguide and guide this general class; to provide for reducing the platefunction t0 keep the pilot DlOperlY centered number of iittings requiredfor a. system of this Withrespect to the rear end of the breach. A kind;to provide hydraulic apparatus for these pitman 32, Fig. 3, is plvotallyconnected to the purposes and having an improved circulatory plunger 'M3and to 'a crank arm 33, the latter be- 00 'I'his invention relates tohydraulic means for imparting a back and forth, intermittent, orresystem; and also to improve the construction and arrangement of partsof apparatus, of this charing fast on a shaft 34 which is supported inbearings 88 (Fig. 1) carried by the frame. The underside of the crankarm 88, as shown in Fig. 3 is in the form of a sector adapted to engagea rack 31 which is slidable longitudinally on the upper exterior surfaceof an auxiliary cylinder 88. Movement is imparted to the rack 81 byactuating the auxiliary piston 39 in the auxiliary cylinder, the pistonrod 4| being connected to a depending lug 42 formed on the end of therack so as to operate the latter. The auxiliary cylinder is providedwith ports 43 and 44 for admitting and discharging pressure fiuid.

The stock to be broached, Fig. 3, may be positioned manually but isvpreferably delivered through a chute 46 to a stock carrier orcross-head 41 when the latter is in its withdrawn position as shown inFig. 1. The stock may be supported upon the stock carrier by means ofbrackets or lugs (not shown) in the manner disclosed in myaforementioned prior patent, No. 1,481,437, or as disclosed in myapplication Serial No. 424,557, filed January 30, 1930 (issued April 25,1933, as Pat. No. 1905,505). The cross-head 41, Fig. 1, is mounted forreciprocatory movement in guideways 48 disposed longitudinally along thesidey members I5 and I1 and motion is imparted to the cross-head, Figs.1, 2, 4, by the piston rods 48 which are connected to the cross-head andto pistons 5| operating in power cylinders 52. As shown in Figs. 1 to 4these cylinders are sup'- ported in the transverse end member I4 and inthe intermediate transverse member 2|. The heads of the cylinders, Fig.4, are connected byy tension rods 53 in a manner more fully illustratedin my aforementioned application, Serial No. 433,490 (Patent No.1,936,073). 'These cylinders are provided with ports 54 and 58 foradmitting and discharging pressure uid for operating the cross-head.

After the stock has been'positioned -onthe cross-head 41 and before thelatter is advanced, the pilot 26 is advanced to the rear end of broachto take the thrust of the cut during movement of the stock over thebroach. The front center 51 is advanced to engage the front end of thebroach for properly centering and supporting the same. This center, Fig.3, is carried by a center-retaining member 58 which is cylindrical inform and carries an exterior rib 58 which en- Sages an interior shoulderin the cross-head 41 when the latter is in its withdrawn position asshown in Fig. 1. The center-retaining member 58 is supported forlongitudinal movement in a sleeve 6I carried by the end member I8 andheld in fixed position therein by a bracket 62 aiflxed to the endmemher. The outer end of the center-retaining member 58, Figs. 3, 1, isenlarged in the form of a plunger 88 which is slidably received in thecounterbore 84 in the sleeve and this end of the center-retaining memberalso .has a longitudinal bore 86 in which a tubular member 81 isdisposed. 'I'he outer end of the tube 81 is connected to the bracket 52and to a pipe connection 88 carried by this bracket. As fluid isadmitted through the tube 51 the centerretaining member 58 will bedisplaced to advance the center. The detailed construction andarrangement of the parts of this front center is further illustrated inmy application Serial No. 424,559, flied January 30, 1930 (issued April25. 1933, as Pat. No. 1,905,508). Pressure-fluid for operating the mainpower cylinders 52 as well as auxiliary cylinder 88, Fles. 3. 4, and thefront center 51 is delivered by a constant speed, variable delivery,reversible iiow pump 1|, Fig. 3, which is driven only in one directionby a suitable motor 12 through a coupling 13, reversal of flow beingeifected without reversing the direction of rotation of the pump.

The port 58, Fig. 4, in the rod end of each of the main cylinders 52 isconnected through the pipe 14, the T 15 and the pipe 11 to one of theports of the pump 1|. The port 54 at the head end of each cylinder 52 isconnected through pipe 18 to the other port of the pump and it will beunderstood that when the pump is operating to denver aum through theconnections 11, 1s one 14' to the port 58 the piston 5| will bedisplaced from right to left as shown in Fig. 4 and the crosshead 41will be moved to advance stock over the broach, this being the workingor cutting stroke of the machine. During this stroke fluid will bedischarged from the port 54 through the connection 18 to the pump 1|.After the completion of this stroke the 110W will be reversed so thatfluid is delivered through the connection ,18 to the head end 54 of thecylinders 52 and fluid will be discharged from the rod end 56 of thesecylinders.

It will be observed that the eiiective area of the rod end of the piston5| is less than the effective area of the head end of this piston due tothe space occupied by the piston rod 49. For good economy it' isdesirable to keep the capacity of the pump as low as is consistent withgood performance and assuming that this pump has suicient capacity onlyto advance the cross-head 41 at the desired rate of speed during theworkingstroke, it will be seen that when the same volume of fluid isdelivered to the head end of the cylinder to return the cross-head thisvolume will only be capable of returning the crosshead at a slower rateof speed than that at which it was advanced. For example if the capacityof the pump were required to advance the crosshead at a speed ofapproximately 29 feet per minute the pump, due to the larger volume andeifective area in the head end of the cylinder, might only be able toreturn the cross-head at a speed of approximately 25 feet per minute. Inorder to conveniently and effectively accelerate this return stroke,concentrate the-control of the mechanism at a convenient point foroperation and repair, and also reduce the amount of piping, connectionsand valves therefor. a control unit 88, Figs.-5, 6, 7, is interposedbetween the pump and the power cylinders 52; A connection 82` extendsbetween this control unit and the port 58 at the rod end of the cylinder52 and a connection 88 also extends between the control unit and theport 54 at the head end of the cylinder 52. As shown in Figs. 5, 6 and7, this control unit has a delivery passage 84 which affordscommunication between the connection 83 and the connection 18 of thepump. The connection 14- of the pump also extends to this control unit.

The control unit 88, Figs..5, 6, comprises a body formed preferably ofan intermediate section 81 and end sections 88 and 89, the passage 84being disposed wholly within the end section 88. The end section 88 hasa delivery passage 9| extending therethrough, the ends of the passagebeing closed by plugs 82, 88 which are threaded therein. A valve ring 84is threaded .into the passage against an interior shoulder 85 andprovides a seat for the valve disk 81. A cylindrical wall 88 extendsupwardly from the valve disk and is preferably formed integraltherewith. A series of longitudinally disposed circumferentially spacedslots are formed in the wall 98 to permit uid to flow freely throughthis wall. A valve cage 99 has its `cylindrical lower portion threadedinto the upper end of the cylindrical wall 98 of the disk 91. Ports |0|are formed in the cylindrical base portion of the valve cage and atubular section connects the base with a plunger |02 which operates in-adash pot |03 formed in i the plug 92. The plunger |02 is provided withvalve cage. i

ports |04 and with a central bore |06 which slidably receives the stemof the valve |01. The seat for this valve is formed on the upper side ofthe valve disk 91, the valve being normally held on its seat by a spring|08 which is disposed about the valve stem and seats against the base ofthe A hollow cylindrical extension l|09 depends from the lower side ofthe valve disk 91 and is reduced at its lower end to flt within a springl I, the upper end of which seats against the shoulder formed on thecylindrical extension. 4Ports ||2 are formed in the walls of thisextension and a port 3 extends longitudinally through the end thereoffor affording communication between the valve |01 and the passage 9|. Anabutment member ||4 serves as a'seat for the lower end of `the springand has a cylindrical extension ||6 disposed within the spring. Thisabutment member is slidably received in a cylindrical recess I|1 formedin the plug 93 and is supported in adjusted positions in this recess byengagement with an adjusting screw ||8 threaded through the end of theplug. A suitable number of gaskets ||9 are disposed between the head ofthe screw and the plug for preventing leakage at this point, and it willbe understood that upon adjustment of the screw one or more of thesegaskets may be added or removed to regulate and control the pressure ofthe'fluid which actuates the front center.

The intermediate section 81 is provided with upper and lower transverseorcross passages. |2| and |22. The upper passage has annular recesses|23, |24 formed adjacent the ends thereof and a. shuttle valve |26 isdisposed in the upper passage for controlling the iow of fluidtherethrough. This valve comprises a rod |21 having oppositely disposedvalve disks |28, |29 secured thereon by means of nuts |3I which arethreaded upon the reduced end portions'of the rod and with a pluralityof short, radially extended wings |3|A positioned thereon substantially90 apart circumferentially of the rod to position and guide the rod inthe passage |2|. Seats |32, |33 are formed in the upper passage and areadapted to receive the valve disks |28, |29 respectively. A pipeconnection |34 extends into the annular recess |23.

The lower passage |22 is preferably a straight cylindrical passagehaving annular recesses disposed at the ends thereof to receive theannular seats |36, |31 for a shuttle valve |38. This shuttle valve has ahollow cylindrical body |39 which is formed integral with a transverseend wall |4|. This end Wall has a central port |42 and a. seat |43 for aone way valve |44, this valve being normally held on its seat by aspring |46. An annular member |41 is threaded into the end of'thecylindricalbody |39 to provide a seat for the spring |46 and this member|41 is also provided with ports |48, |49 to permit uid to ow freelythrough this portion of the valve body when the valve |44 is in openposition. The end section '89 is provided with upper and lower ports|5|, |52,

tion and afford communication between these passages and the passage 9|in this end section.

'I'he end member 88 is also provided with upper and lower ports |53, |54which register with the adjacent ends'of the passages in theintermediate section and aiord the communication between these passagesand the passage 84 in the section 88. The adjacent surfaces of the endand intermediatesections 81 to 89 have complementary interflttingprojections |55 which assist in holding the various passages inalignment. The end and intermediate sections may be secured together inany approved manner, as by means of bolts (not shown).

A choke valve |56 is mounted upon the section 88 and comprises a bodyportion |51 which may be formed integral with this end section as shown.A pipe connection |58 extends into the body |51 of the choke valve and a-right angle passage |59 extends -between the connection 4|58 and a port|6| which affords communication between the passage 84 and the passage|59. 'I'his passage,

Fig. 9, |59 is enlarged to provide a seat |62 for a one way valvecomprising a spherical member |63 which is normally held on its seat bya coil spring |64. This spring is mounted upon a pin |66 carried by aplug |61 which is threaded into the end of the passage |59. Anotherpassage |68 extends from the connection |58 Vand has a restrictedportion |69 for restrictingthe ow between the portV |6| and theconnection |58. For convenience of rmanufacture the passage |68 may bedrilled from the side of the body |51 and closed with a plug |1| asshown, the restricted portion being drilled from the passage 84.

The pipe connection |34 on the intermediate section extends to the port43 at the head end of the auxiliary cylinder 38 (Fig. 3) and the conthepump.

A fluid reservoir or supply tank |8| (Figs. 1 and 3) is supported uponthe transverse members I8 and I9 of the bed plate and a connection |82extends between the bottom of this supply tank andthe upper passage |2|of the intermediate section of the control unit. This passage 2| alsohas a port |83 and a connection |84 extends i between this port and thepump for permitting iluid to flow by gravity from the supply tank to thepump, the supply tank being preferably open to the atmosphere.

Means are also provided for automatically reversing the flow of the pumpas the cross-head or stock carrier reaches either end of its stroke. Asshown in Figs. '1 and 2 a rod |9| is mounted to slide longitudinally inbearings |92 supported by the frame. Collars |93, |94 are disposedadjacent the ends of the rods and are preferably arranged to beadjustable longitudinally of the rod so thatV they may be heldin variouspositions. If desired set screws (not shown) may be provided for holdingthese collars in selected positions. An abutment member |96, Figs. 1, 2,is mounted upon the cross-head 41 in aposition alternately to engage oneof the collars as the cross-head approaches the ends of its stroke. therod to move longitudinally in its bearings with the cross-head, thearrangement being such that the rod is moved to the right as shown inThis Iengagement causes Flgs. 1, 2 and 3 when the cross-head is moved toits withdrawn position and the rod is also moved to the left as thecross-head nishes its working stroke. A rack |91 (Fig. 10) is formed onthe underside of thenrod |9I at the end thereof and is'engaged by a gearsector |98, the latter being mounted onV a shaft |99 which is rotatablysupported in the bracket 200 mounted upon the end member I3 of the'frame. An arm 20I, Fig. 3, is xedly connected to the shaft |99 and theouter end of this arm has a slot which iits over the rod 202, the armbeing held pivotally thereon by round faced nuts 203. In a similarmanner the longer arm of a bell-crank 204 is pivotally connected to thelower end of the rod 202 While the shorter arm of this bell-crank ispivotally connected to a rod 206. This bell-crank is mounted to pivot onthe pedestal II. The rod 206 is also pivotally connected to a bell-crank201 arranged to operate a control plunger 208. It will be understoodthat when the rod |9| is moved to one of its extremepositions thelinkage just described will be effective to reverse the flow in the pump1I and that when the rod is moved to the other of its extreme positionsby engagement with the abutment |96 the sector |98 will be moved in theopposite'direction again to reverse the flow.

In the operation of the apparatus with the parts arranged and shown asin Fig. 1 fluid is delivered by the pump through the connections 11 tothe T 16 and from this T through the connection 68 to the interior ofthe center retaining member 58 to advance this member. The rib 59 on thecenter retaining member however is at this time in engagement with aninterior shoulder formed in the cross-head 41 so that the centerretaining member 58 can not advance until the cross-head has first movedthe stock to be breached on to the end of the broach. l

Fluid is also delivered by the pump from the connection 11 through the T16 and the connection 14 to the upper end or chamber 9|a of the passage9| in the Icontrol unit (Fig. 6). When fluid rst enters this passage 9|athe valve 91 is held on its seat by the spring III and the uid isdiverted through the port I 5I to the annular recess or chamber |23 andth'e pressure of the fluid of this chamber acting against the valve disk|28 of the shuttle valve |26 forces this disk against its seat to closethis end of the upper passage I 2| Fluid then ows from the chamber |23through the connection |34 and port 43 to the head end of the auxiliarycylinder 38 and moves the piston 39 from right to left as shown in Fig.3. This movement of the piston 39, due' to its connection with the rack31, serves to rotate the crank arm 33 in a clockwise direction toadvance the pilot 26 into engagement with the end of the broach. Byadjusting the tension on the spring III by means of the screw I`| 8 thepressure in the auxiliary cylinder may be maintained at the proper valueto advance the pilot at the desired rate of speed to engage the broachbefore the cross-head is moved. When the pressure in the upper end ofthe passage 9|* attains a predetermined value the valve disk 91 will bemoved oi its seat against the action of the spring I I I and fluid willthen flow from the connection 14 through the passages 9|, 9|, andthrough the lower port |52 into the lower passage |22. On entering thispassage the iiuid will move the shuttle valve |38 to the left as shownin Fig. 5 to close this end of the passage |22 and uid will then flowfrom the passage |22 through connection 82 to the port 56 (Fig. 4) atthe rod end of the power cylinder 52, thereby displacing the piston 5|from right to left and causing the crossv head 41 to advance the stockover the broach for the working stroke. As the cross-head approaches theend of this working stroke the abutment |96 (Fig. 1) will engage thecollar |94 and move the rod |9| to reverse the flow through the pump. Onthis reversal of flow the connection 14 becomes connected to the suctionside of the pump and hence will tend to draw uid out of the passage 9Ithrough ports ||2, ||3 lifting valve |01 and back to the pump throughthe chamber 9| and the connection 14. The connection 18 is now connectedto the delivery side of the pump and fluid passes through thisconnection into the passage 84 of the control unit and out through theconnection 83 to port 54 at the head end of the cylinder 52. Thepressure developed in the passage 84 in the control unit is effective tomove the shuttle valve |38 from the position shown in Fig. 5 to theother end of the passage |22 as shown in Fig. 6. Fluid also passes fromthe passage 84 through the upper port I 53 to the annular chamber |24where it is effective to move the valve disk |29 onto its seat |33,thereby closing this end of the upper passage |2I.

When the shuttle valve |38 has moved to the position shown in Fig. 6,fluid is permitted to ow from the delivery side of the pump through theconnection 18 and the passage |22 to the connection 82 which aordscommunication with the port 56 at the rod end of the cylinder 52.Pressure iluid is thus delivered to ports at both ends of the maincylinder 52 but as the head end of the piston has a greater effectivearea than the rod end, the diierential pressure will be effective tomove the piston from left to right as shown in Fig. 4 to return thecross-head 41 to the position shown in Fig. 1. As this movement of thepiston is initiated iluid is forced out of the cylinder through theportl 56 and back through the connection 82 into the passage |22 andinto the passage 84. It'will be seen therefore that during this strokethe rod side of the piston 5I acts as an auxiliary pump to force fluidthrough the connections just poined out from one end of the cylinder tothe other. At vthe same time that the piston is functioning in thismanner to by-pass uid from one end of the cylinder to the other, thepump may be operating at capacity to deliver fluid into the passage 84and into the head end of the cylinder. This arrangement makes avail-.able a very large volume of uid for displacing the piston on its returnstroke and it will be apparent that the return stroke may be made veryrapidly.

In such cases it has been found that the crosshead is returned in thismanner with greater speed than is required and furthermore the highpressures resulting from this combined flow and increased volume arealways far in excess of those to which the auxiliary cylinder and pipingshould be subjected. The use of such high pressures in this auxiliarycylinder subjects the cylinder, the piston and piping as well as thepilot operating mechanism to unnecessary strain and wear. In many caseswhere it has been attempted to use such pressures in the auxiliarycylinder the piping has been blown out. Occurrences of this kind'areavoided with the present apparatus by the arrangement of the choke valve|58. It will be seen` that when pressure uld is admitted to the chokevalve |56 (Fig. 9) through the port I6I from the passage 84 thespherical member |63 will be forced on its seat to close the passage |59and iiow to the connection |58 rparticular time to be connected leadingto the port 44 will be retarded by the restricted passage |69. Thisassures that lluid at these higher pressures will be delivered throughthe connection |58 and the port 44 to the rod end of the auxiliarycylinder at a permissible rate and hence the parts operated by thiscylinder will function in their intended manner. It will also be seenthat when th-e piston 39 of the auxiliary cylinder is moving from rightto left as shown in Fig. 3 the pressure of this fluid will move thespherical member |63 from its seat, Fig. 8, and normal flow will bepermitted through the passage |59 and the port 6| to the passage 84 andto the suction slide of the pump.

In order further to assure that damage will not be caused to theauxiliary cylinder or to the main cylinder 5| or any of the connectionsor parts operated by these cylinders, the one way relief valve |44 isadapted to'open at such pressures as are considered proper. It will beseen from Fig. 7 that when this valve opens fluid may be bled throughvthe shuttle valve |38 into the passage 9| and that the pressures thereinwill be eifective through the ports, H2, ||3 to raise the valve |01 fromits seat, thereby permitting the fluid to be returned to the suctionside of the pump. Should the pressure of the fluid be decreased belowthe" value to which the valve |44 is set to open it will be apparentthat .this valve will again close.

The functionof the port |83 in the shuttle valve |26 is to keep theinlet of the pump submerged through connection |84 (Fig. 3) at all timesso that the pump may be supplied with fluid from the supply tank |8|. Itwill be apparent that fluid is permitted to flow by gravity from thesupply tank through the connection |82 into theupper passage |2| and outthrough the port |83 and through the connection |84 to the pump tocompensate for leakage and for variation in the quantity ofoil requiredin the system. 'Ihe shuttle valve |26 is so arranged that it is alwaysopen to alford communication with whichever of the passages 14 or 18happens at that to the suction side of the pump.

By arranging the various connections and valves in the control unit 86it is possible greatly to reduce the number of ttings required in asystem of this general character and also to centralize the variousinstrumentalities which control the system. In one particular instancethe number of fittings required were reduced by this arrangement fromapproximately 45 or 50 to 17. It will also be seen that by forming thebody of the control unit 86 of separable sections 61, 88 and 89 thevarious passages may readily be formed by relatively simplemanufacturing operations and the various valves and connections mayeasily be assembled in operative positions and are readily accessiblefor adjustment.

I claim:

1. The combination with a pressure -cylinder having a piston, and aconstant speed, reversible flow pump, and a pressure iiuid reservoir, ofa control unit between and connecting the pump and cylinder and having abody, separate delivery passages from opposite sides of the pump throughthe body to opposite cylinder ends; an upper cross passage between thedelivery passages connected also with the reservoir; a lower crosspassage having a shuttle valve and connecting the delivery passages, ableed passage through said shuttle valve; a shuttle valve in the uppercross passage closing it between the delivery passages when the flow isin the rst delivery passage, while opening the cross passage between thereservoir and the second delivery passage; the valve in the lower crosspassage closing the same between the delivery passages to permit ow fromthe rst delivery passage to the rst cylinder end; and upon flow reversalsaid Valve in the upper cross passage closes the connection between thedelivery passages and connects the rst delivery passage to thereservoir; and the valve in the lower cross passage opens connectionbetween the second delivery passage and the first end of the cylinder,which flow is, as well, to the cylinder end opposite to said first end;the bleed passage in the lower cross passage opening when the flow inthis reverse direction attains predetermined pressure to permit flowthrough the bleed passage to the rst delivery passage.

2. The combination with a power cylinder and a reversible flow pump forsupplying pressure fluid to the cylinder, of a control unit comprising abody, means providing separate passages from opposite sides of the pumpthrough said body to opposite ends of the cylinder, said body having apassage means connecting said separate passages, a shuttle valve forcontrolling the ilow through said passage means forclosingone of saidseparate pasages between the pump and the passage means, andpressure-responsive means carried by the shuttle valve for bleedingiluid from the passage means to said separate passage.

3. A control unit for connection between a reversible flow pump, a fluidreservoir and a power cylinder, said unit comprising a body havingdelivery passages through it for connection between opposite sides ofthe pump and opposite ends of the cylinder, and having a supply passagefor connection between the lluid reservoir and the pump, an upper crosspassage in the body andv between the delivery passages constituting.said connection, and a shuttle valve in said cross passage operable bythe uid pressure in one of the delivery passages to close said passageto thereservoir; and a lower cross passage between said deliverypassages with a shuttle valve therein operable to permit pressure fluidilow from one of said delivery passages to one end of the cylinder andalso, on reversal, flow from the other delivery passages to both ends ofthe cylinder sirnultaneously, and subsequently ow from one cylinder endthrough said cross passage and through said delivery passage to theopposite cylinder end; said body having auxiliary passages leading fromeach of the delivery passages for connection to the opposite ends of anauxiliary fluid cylinder, one of said auxiliary passages comprising aplurality of ducts of diierent sizes, pressure responsive means fornormally closing the larger duct, thus restricting the flow through thesmaller duct, and to the auxiliary fluid cylinder, the pressureresponsive means being operable to provide for normal ow from theauxiliary uid cylinder; and means for closing one of the deliverypassages until the pressure in the auxiliary passage associatedtherewith attains a predetermined value.

GEORGE J. RUSSELL.'

